Claire Raphael, MBBS: I'm Dr Claire Raphael, one of the cardiology fellows at Mayo Clinic. Today we'll be discussing lifestyle modification for atrial fibrillation. I'm joined by Dr Suraj Kapa, who specializes in arrhythmia disorders. Welcome.
Suraj Kapa, MD: Thank you, Dr Raphael.
Dr Raphael: How do weight and fitness play a role in atrial fibrillation?
Dr Kapa: Weight and fitness play multiple intersecting roles in atrial fibrillation. Atrial fibrillation can be an incidental organic disease that happens in anybody, but it can also be the result of an accumulation of factors that can occur in any given person. What I mean by this is the interplay between other forms of heart disease, diabetes, or hypertension as well as other factors including increased weight or poor fitness, can all lead to the pathophysiology or underlying tendency to develop atrial fibrillation. Extensive data show that obesity actually contributes to changes in the heart itself.[1,2,3] Diastolic dysfunction as well as increased left atrial size can be the result of obesity or morbid obesity, which can in turn lead to an increased risk for atrial fibrillation.
Fitness is more interesting because both poor fitness—as well as being overly fit—can increase the risk for atrial fibrillation. When you are very unfit, you have a higher tendency of being obese, which can in turn lead to an increased risk for atrial fibrillation. There are also data that excessive fitness—doing things such as marathon running or engaging in extensive aerobic activity—can increase the risk for atrial fibrillation because of similar changes in cardiac structure and function. Increasing fitness can increase hypertrophy of the heart, which can in turn lead to diastolic dysfunction and increased left atrial size.[4] The interplay is complex, but it makes pathophysiologic sense for why patients who have excess weight or either poor or excessive engagement in fitness can develop atrial fibrillation.
Dr Raphael: It sounds pretty complex. What about weight loss? How does that impact the treatment of atrial fibrillation?
Dr Kapa: In the past couple of years weight loss has been shown to play a very interesting role in treating atrial fibrillation. Numerous studies have come out of more than one center showing that if patients with a body mass index (BMI) > 27 kg/m2 were to lose at least 10% of their body weight (not even getting back to a normal BMI) through a structured fitness program, this results in a reduced risk for atrial fibrillation.[5,6,7] Specifically, in patients who have atrial fibrillation, up to 70% can eliminate their atrial fibrillation without using medications or undergoing any invasive procedures, simply by losing weight.
Dr Raphael: You mentioned that it takes about a 10% weight loss. What do you normally advise patients in terms of weight loss and who might benefit?
Dr Kapa: A lot of components go into this. It takes at least a 10% weight loss, but there are other factors. If you are already normal weight, losing more weight is probably not going to help you. We have to think of that subgroup of the population that is obese, and by that I mean a BMI > 27 kg/m2. That's the subgroup that most of the studies have focused on.[5,6,7] Other interesting elements have come out in these studies. First, there is the element of how one loses weight. Losing some weight but then gaining it back and losing it again—having these weight fluctuations does not confer as much benefit as when a person has what we call "linear weight loss"—in other words, a slow gradual weight loss over time. The other element is fitness. There is an interplay between losing weight and improving fitness in terms of the benefit to atrial-fibrillation management.
Dr Raphael: How would you measure fitness?
Dr Kapa: The standard measure of fitness that we use within medicine is "metabolic equivalents." By measuring how far patients can go on a standardized treadmill test, we can determine what their fitness level is, but it can be very difficult. Even though that is the most subjective measure we have, it's still not quite exact. We need to allow patients to go as far as they can reasonably go on that treadmill to determine their fitness level. Some patients are very unfit even though they look quite lean, and there are other patients (such as football players) who can by all standards of BMI be obese but are incredibly fit and probably run faster and harder than any person with a normal BMI. That's why fitness is difficult to assess, and why a lot of the data relate to the general population of people who are overweight or obese, who don't exercise or do very much activity at all. The data are not as relevant to the athlete who might be "obese" or to patients who are thin but poorly fit.
Dr Raphael: What do you recommend to patients to achieve weight loss and improve fitness?
Dr Kapa: I explain that a structured gradual approach is critical, and this includes talking to your physician about how you assess what you are doing day to day. This includes talking about diet and what type of exercise to engage in and what targets should be used. We're not talking about trying to run a 5K within a month. We're talking about trying to exercise from 20 minutes to as much as an hour at least 3 to 5 days a week, trying to reach a target heart rate of 220 bpm minus the person's age times 80%, and trying to gradually uptitrate that, in addition to watching what they eat to achieve both the weight loss as well as the improvement in fitness.
Dr Raphael: Do you feel this is a conversation that electrophysiologists should be having routinely with their atrial-fibrillation patients, or do you think this is more the role of the general cardiologist or the primary-care clinician?
Dr Kapa: It's relevant to everybody. This should be applied in relation to medications and invasive therapies. It's relevant at every point in the history of the patient's atrial fibrillation. It has been shown in most of these studies that weight loss and improving fitness level in this specific subgroup of patients has benefit in all phases.[4,5,6,7] This has benefit in the patients who have never tried medication or undergone an invasive procedure, but it has also been shown to be complementary in terms of improving the efficacy of both medications and invasive therapies.
The reality is that atrial fibrillation is a very common disease. Some people say that if you monitor everybody on earth for long enough and they live long enough, they will probably have some atrial fibrillation at some point in their lives. This isn't just an electrophysiologist's problem, it's also a general cardiologist's and a primary-care physician's problem. Weight loss and improving fitness aren't prescribed only by electrophysiologists. Any cardiologist or primary-care physician should be able to guide their patients through this.
Dr Raphael: You mentioned that weight loss and exercise are complementary therapies. Is this something that should be tried before trying other medications or invasive therapies, or do you think it should only be done in combination with other therapies?
Dr Kapa: That's where a discussion with the patient comes into play and we talk about shared decision making. If you have a patient who is always in atrial fibrillation, with profoundly diminished functional capacity because of it, it would seem very unreasonable to expect that patient to engage in regular exercise. If you have a patient who is only mildly symptomatic or paroxysmal, it might make sense to try weight loss and exercise as an initial therapy. The truth is, we don't know in a randomized fashion whether it is better to aggressively target weight loss and improving fitness right away and hold off on medication and invasive therapies as long as possible, or if it makes sense to do everything at the same time. We don't have any randomized data. As the years go by we will get more data on that to inform us better.
Dr Raphael: Thank you very much Dr Kapa. You've given me a lot of insight about a condition that is very common but something I have actually never prescribed to a patient. Thank you for joining us on theheart.org on Medscape.
© 2017 Mayo Clinic
Cite this: Lifestyle Modification as Therapy for Atrial Fibrillation - Medscape - Jan 06, 2017.
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